About Rs 200 crore of unaccounted income has been detected in the past week in surveys conducted by the income tax authorities in Ahmedabad and Surat, an official said Tuesday.

Two builders of Ahmedabad disclosed unaccounted income of Rs 100 crore after a survey by the department that ended Monday.

While one builder disclosed unaccounted income of Rs 75 crore, the other revealed an income of Rs 25 crore. D S Rastogi, chief commissioner of the income-tax department, said Tuesday that a survey was in the offing in all cases where advance tax paid this year was lower than that of last year.

In a similar operation in Surat, the income-tax authorities detected unaccounted income of Rs 90 crore from seven firms involved in textile trading and real estate, official sources said.

With sealed bank lockers and documents still being scrutinized, the amount may well cross Rs 100 crore, it was pointed out.

The investigation wing of the income tax department which conducted the Surat operation termed it as one of its biggest, with one textile company alone disclosing Rs 38 crore of unaccounted income while the remaining partnership firms disclosed a total of Rs 52 crore.